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Within our Central London portfolio we hold almost the entire freehold to Regent Street and nearly 50 per cent of the buildings in St James's. Across the portfolio we are currently delivering a £1.5 billion investment and redevelopment programme.

How does the map work?

The Crown Estate has been a major player in the development of the UK’s offshore wind industry since its beginnings a little over a decade ago. As an active asset manager of the seabed, we award leases and capitalise on our unique overview to bring the sector together to overcome common challenges and help unlock value from this natural asset.

We manage the seabed out to the 12 nautical mile territorial limit under the auspices of the Crown Estate Act (1961), and it is under the Energy Act (2004) that we have responsibility for renewable electricity generation within the UK Economic Exclusive Zone which extends to the limits of the UK continental shelf.

The UK now generates more electricity from offshore wind than any other country in the world and is the most attractive country to invest in globally (ref. EY index). In just 15 years this sector has developed and matured, and it now has a measurable impact on the national energy mix with around 12% of the UK’s electricity requirements being met during periods of peak generation.

From the first two demonstration turbines deployed offshore at Blyth in 2000, there are now nearly 1,500 turbines operating 26 wind farms. That's an installed capacity of more than 5 GW, meeting on average over 5% of the national electricity demand – enough to power 4 million homes. With the benefit of a strong development pipeline, this is set to rise to around 10% of UK electricity requirements by 2020.

We have developed an interactive map showing ‘real time’ power generation, the wind speed and direction, and supplementary information as to where offshore generation fits into the national energy mix.

The map, which amalgamates data from various sources (see below for more detail) and updates hourly, shows the estimated total electricity being generated as well as each individual projects’ contribution.

It demonstrates the significant contribution that offshore wind is already making to a low-carbon and secure energy mix whilst the additional information provided highlights the benefits these large infrastructure-scale projects are making.

Where does the data come from?

In order to present as close to real time generation data as is available, the map draws information from several sources as outlined below.

Operational metering

National Grid and offshore wind farm operators monitor generation in real time using meters which measure the instantaneous megawatt (MW) output on the power stations. Typically this data is confidential to the system operator and the wind farm operator. We will publish operational metering data for those wind farms where the operator publishes this information. We will also publish aggregated data reported to the market by National Grid via Elexon, who have responsibility for collecting and publishing market data.

Final physical notifications

Under the market arrangements most offshore wind farm operators publish forecasts of their output. Elexon also publishes this data, known as Final Physical Notifications (FPNs), to the market an hour before the half-hour to which the forecast refers. We use this FPN data as a forecast of output for the wind farms that notify in this format (typically, but not necessarily, with a capacity of greater than 50 MW).

Forecasts

For those wind farms for which FPNs aren't available, an algorithmic approach is used to forecast the output. Calibrated turbine output curves from the manufacturer are used, coupled with expected availability numbers and a publicly available weather forecast (Global Forecast Systems [GFS] at 0.5 degree resolution) from the National Oceanic and Atmospheric Administration in the United States. Forecast accuracy is monitored against settlement metering outputs.

Settlement metering

The company which gathers the data for the UK electricity market is called Elexon; it publishes half-hourly generation numbers for many of the offshore wind farms from settlement data. This settlement data is published to the market five working days after generation. This data is the most accurate data on the operation of the power stations but obviously not timely enough for understanding what the fleet is producing in any given hour. It should also be noted that not all wind farms are reported by Elexon, as some smaller wind farms are metered in separate arrangements by their host energy suppliers and there is no public visibility on the output of these stations.

Wind speed and direction

The wind speed arrows are forecast GFS wind speeds measured in mph and taken from forecasts every six hours at 0.5 degree resolution.

Lower panel

Located at the bottom of the map is a panel containing numbers featuring the latest offshore generation forecast other forms of generation contributing to the UK energy mix.

Latest generation forecast

This data comes from the published FPNs, or otherwise from the forecast as explained above.

Estimated share of UK electricity currently being generated by offshore wind

This calculation expresses the sum of the FPNs declared for offshore wind stations plus the forecasts where used, as a percentage of the national figure, calculated using the fuel type level half hourly average operational metering generation from National Grid published by Elexon for all fuel types.

Generation comparison

Coal

This is the aggregate average coal power station output in MW published by National Grid via Elexon for the current hour. This includes all major coal power stations that supply power to the National Grid. Coal generation sites which are either supplying industrial demand or small are ignored.

Gas

This is the aggregate average gas power station output in MW published by National Grid via Elexon for the current hour. This includes all major combined cycle (CCGT) and open cycle (OCGT) power stations that supply power to the National Grid. It does not include reciprocating peaking plants and small generation sites which are supplying industrial demand.

Nuclear

This is the aggregate average nuclear power station output in MW published by National Grid via Elexon for the current hour. This includes all nuclear power stations that supply power to the National Grid.

Side panels

'Output' generation data

At the right hand side of the map is a panel containing numbers relating to current and longer-term output:

Estimated share of UK electricity currently being generated by offshore wind

This calculation expresses the sum of the FPNs declared for offshore wind stations plus the forecasts where used, as a percentage of the national figure, calculated using the fuel type level half hourly average operational metering generation from National Grid published by Elexon for all fuel types.

The highest output recorded on a single day in the last calendar month in GWh (gigawatts per hour).

This calculation identifies the highest day of aggregated electricity production in the previous calendar month, using daily settlement metered data where available and a forecast is used where the settlement metered volume is not published. Because settlement data is used, this number will normally be updated and published for the previous month ten days after the end of each month.

The total energy generated by offshore wind in the previous month

For this monthly data settlement metered data is used where available and a forecast is used where the settlement metered volume is not published. This number is in gigawatts per hour or GWh (i.e. 1,000s of MWh). Because settlement data is used, this number will normally be updated and published for the previous month five working days after the end of each month.

The total electricity generated by offshore wind year to date

For year to date generation, the monthly figures from settlement data are used alongside forecast data where the settlement metered volume is not published. This number is in terawatts per hour or TWh (i.e. 1,000,000s of MWh). Because settlement data is used, this number will normally be updated and published five working days after the end of each month.

The total electricity generated by offshore wind in the last 12 months

For annual generation, the monthly figures from settlement data are used alongside forecast data where the settlement metered volume is not published. This number is in TWh (i.e. 1,000,000s of MWh). Because settlement data is used, this number will normally be updated and published five working days after the end of each month.

'People' data

At the right hand side of the map is a panel containing numbers relating to the industry's contribution to the job market:

The level of direct employment in the industry

This figure was taken from the Renewable UK (RUK) report ' Working for a Green Britain & Northern Ireland 2013–23'.

'Environment' data

At the right hand side of the map is a panel containing numbers relating to offshore renewable, low-carbon energy:

Operational time taken for the Siemens 6 MW turbine to have generated enough energy to be carbon neutral over its lifecycle. This figure was taken from Siemens publication ‘A clean energy solution– from cradle to grave’.

The amount of diesel that would release 0.86 tonnes of CO2 saved by generation of 1 MWh of renewable energy. This was established by calculating the amount of oxygen required to combust the carbon content of diesel fuel, and from this the mass of CO2 which would have been produced.

Number of homes that offshore wind generated enough electricity to power in 2014. Calculated by dividing total generation from offshore wind by the average UK annual household electricity usage (as published by DECC).

'Did you know?' data

At the right hand side of the map is a panel containing general numbers of interest.

1 MWh of energy can power…

These are indicative, 'real world' comparisons of what 1 MWh of energy can power. The examples featured are based on calculations which use averages to represent a broad range; for instance there is a wide array of types of cars or refrigerators with different levels of performance. These numbers are indicative only and serve to help illustrate the concept of 1 MWh.

Individual project offshore generation data

The estimated output of each wind farm shown in the data view is the most accurate indication of current wind farm output to the nearest hour. It will either be the FPN or a forecast of the output using GFS wind, calibrated turbine performance curves and estimated availability.

The capacity of the site is the number of turbines multiplied by the published power rating or the purchased grid transmission entry capacity, whichever is the lesser.

Correlation with other wind estimates

The Crown Estate “Offshore Wind Electricity Map” (OWEM) is one of a number of web-based monitors which present near real time electricity output based on the same underlying National Grid data source. This note explains why the reported generation attributable to all wind (on land and offshore combined), and offshore wind alone, appear to be conflicting.

OWEM and other sites monitor different fleets; the former covers only offshore wind assets (district network operator (DNO) and transmission system operator (TSO) connected) whilst others generally cover both onshore and offshore wind assets (but only for TSO sites).

The 3.1 GW onshore wind TSO connected fleet, which is monitored by some sites but not by OWEM, is located entirely in Scotland. The 0.7 GW offshore wind DNO connected fleet, which is monitored by OWEM but not by other sites, is almost entirely located off the coasts of England and Wales.

When half-hourly readings are analysed, there is evidently only a very weak correlation between wind speeds experienced in Scotland and those experienced in England and Wales. This is due to the nature of the UK climate which sees substantial metrological variation in both time and space due to the complex confluence of maritime tropical air masses from the south west and maritime polar air masses from the north. Pressure systems drive variation in wind speeds in the order of hours and days; however, the influence of this on regional wind speeds is highly variable.

Over a study period of 3 months during the autumn of 2015/16, these regional differences in weather patterns resulted in the productivity of the offshore wind fleet being at least 4.4 times greater than that of the onshore fleet for 21% of the time, on a MW for MW basis. This condition corresponds to periods when the OWEM output is broadly equal to or greater than that presented by websites reporting wind output only from TSO connected projects.

Other contributory factors include; minor differences in sampling / averaging methods, occasional curtailment of the Scottish onshore wind TSO connected fleet and uncertainty in the estimates of offshore wind DNO connected production. These are considered to be important but of second-order relevance when compared to the metrological findings presented above.

There is no evidence of material errors associated with either OWEM or reviewed sites in the representation of UK wind electricity production on the basis they are derived from the same underlying data from National Grid. The apparent discrepancies can be explained by the combination of differences in the monitored fleets, their location and meteorology.

Disclaimer

The data that is provided as part of this service comes from the www.netareports.com service of EnAppSys Ltd and is provided as a free service, it is provided in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. The data from which this summary is derived contains data that is the copyright of ELEXON and National Grid.

The Crown Estate, its Commissioners, staff and agents shall not be held liable for any loss or damages or expenses of any kind (direct, indirect or consequential) in connection with use of the data.

You are not permitted to copy, sub-licence, distribute or sell any of this data to third parties in any form.

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